#!/usr/bin/env node

const Readable = require('stream');

const rd = new Readable();
const c = 'a'.charCodeAt(0);

rd._read = () => {
  rd.push(String.fromCharCode(c++));
  if (c > 'z'.charCodeAt(0)) {
    rd.push(null);
  };
}
rd.pipe(process.stdout);